Successive cultivation of soybean/corn intercropped with Urochloa Brizantha Topdressed with nitrogen

Abstract

Corn intercropped with Urochloa brizantha (Syn, Brachiaria brizantha) has been indicated as a suitable alternative management practice for rational land use in crop-livestock production systems in the Cerrado region of Brazil. An experiment was carried out in Maracaju, MS, Brazil to evaluate the effect of sequences of soybean/second-crop corn systems intercropped with Urochloa brizantha and the effects of forms of nitrogen on soil chemical and physical properties. A randomized block experimental design was used with four replications; treatments were in a 2 × 4 factorial arrangement with two systems of crop management: second-crop corn intercropped with Urochloa brizantha, and monoculture of second crop corn; and four forms of topdressing N: urea, urea + ammonium sulfate, ammonium sulfate, and no N supply. The following chemical properties were evaluated: soil organic matter and exchangeable K contents, cation exchange capacity, base saturation, and K saturation; as well as the physical properties: soil bulk density and aggregate stability. Crop residue cover and agronomic traits of soybean were also assessed. Intercropping induced significant differences in crop residue cover, plant height, soybean yield, stand, 100-seed weight, soil organic matter, exchangeable K, and K saturation in the exchange complex. There was no significant effect of the crop sequences on soil bulk density and mean weight and geometric mean diameter of water-stable aggregates. No significant effect of forms of N was observed on any chemical or physical properties, or on those related to soybean development.